Changes in the molecular genetic profile of innate immune molecules in individuals who have had COVID-19

In 2020, the COVID-19 pandemic has been declared. Since then, it was revealed that the severity of the disease pathology may depend not only on the viral strain, but also on the functioning of immunity system. The aim of our study was to evaluate some characteristics of expression and genetic factors of innate immunity in patients who have had COVID-19. We have studied scrapings from mucous membranes and venous blood samples taken from 148 patients. Identification of the studied markers was carried out using reverse transcription and RT-PCR methods. Statistical analysis of results was carried out using Mann–Whitney test, Fisher’s exact test, χ 2 test, odds ratio and 95% confidence interval. Our study has demonstrated a prognostic role of polymorphic markers, i.e., haplotypes of TLR9 (rs352140 and rs5743836) and TLR4 (rs11536889 and rs4986791) gene variants related to the risk of severe SARS-CoV-2 infection. When studying long-term effects of COVID-19, we have revealed that an imbalance in the expression of receptor and effector molecules at the mucosal level of immune response remains in patients who had a history of this disease. There was a decreased expression of both receptor molecules (TLR3, TLR7) and antiviral immune response factors (IL-28) in the oropharyngeal mucosa along with general increase of these markers in epithelial cells of nasopharyngeal mucosa. Expression levels and genetic factors of innate immunity associated with severe SARS-CoV-2 infection and, consequently, persistent changes in immune system long after recovery, have been revealed, thus expanding our knowledge of molecular genetics mechanisms associated with prolonged course of COVID-19. The results obtained during the study may help to assess the risks of developing severe infection caused by SARS-CoV-2 and evolving complications in hospitalized patients.